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United States Patent | 5,661,817 |
Hatlestad ,   et al. | August 26, 1997 |
A conventional color charge-coupled-device (CCD) camera without a near infrared blocking filter is used to detect desired vegetation from undesired vegetation and other background. This detection technique relies on the fact that near-infrared (NIR) wavelengths are received by CCD cameras in predetermined frequency bands. This provides output signals from the green and blue pixels of the CCD camera which are approximately equal in interests to the intensity of the infrared portion of the signal provided by the red pixels. A filter is placed between a target area and the CCD camera to restrict the light received by the camera to a bandwidth (approximately from wavelengths of 600-1400 nm), which allows the NIR signal component of the green or blue pixels in this bandwidth to be compared by a signal processing device to the NIR plus R output of the red pixels. In this bandwidth the intensity of the output from the red pixels due to red light from the target area is maximized. Therefore, a signal processing device can utilize signals from the red, green and blue pixels to detect plants and crops in an area of undesired vegetation.
Inventors: | Hatlestad; John David (Burnsville, MN); Sauter; Gerald Francis (Eagan, MN) |
Assignee: | Lockheed Martin Corporation (Bethesda, MD) |
Appl. No.: | 505550 |
Filed: | July 21, 1995 |
Current U.S. Class: | 382/110; 348/144; 348/164; 348/273; 382/164 |
Intern'l Class: | G06K 009/00; H04N 007/18; H04N 009/47; H04N 005/33 |
Field of Search: | 382/110,162-165 348/33,34,144,164,290,291,266,143,148,273 |
3869705 | Mar., 1975 | Woywood et al. | 348/144. |
4015366 | Apr., 1977 | Hall, III | 382/110. |
4227211 | Oct., 1980 | Disbrow | 348/144. |
4718089 | Jan., 1988 | Hayashi et al. | 382/164. |
5132802 | Jul., 1992 | Osthues et al. | 358/213. |
5353053 | Oct., 1994 | Nishioka et al. | 348/164. |
5555464 | Sep., 1996 | Hatlestad | 348/266. |
Franz, E, Gebhardt, M.R., Unklesbay, K.B., "The Use of Local Spectral Properties of Leaves as an Aid for Identifying Weed Seedlings in Digital Images" Transactions of the ASAE, Mar.-Apr. 1991, vol. 34(2), pp. 682-687. Nitsch, B.B., Von Bargen, K., Meyer, G.E., "Visible and Near Infrared Plant, Soil and Crop Residue Reflectivity for Weed Sensor Design," ASAE Presentation, Jun. 23-26, 1991, Paper No. 913006. |